Conventionally, there has been an LED lighting apparatus described in a Document 1 (JP 2013-225393 A), for example. The LED lighting apparatus in the Document 1 (hereinafter, referred to as a conventional example) includes: an LED string constituted by a series circuit in which LEDs (Light Emitting Diodes) are connected in series; a rectifier configured to full-wave rectify an AC voltage; and a light emission controller. In those, the rectifier and the light emission controller are included in a lighting device. The light emission controller performs constant current control for a drive current flowing through the LED string while adjusting the number of LEDs, which emits light, in accordance with a change in an input voltage (a pulsating voltage) supplied to the LED string via the rectifier. Furthermore, a dimmer described in the Document 1 has a TRIAC. By controlling the TRIAC, the dimmer is configured to control a phase of the AC voltage to be supplied from an AC power supply to the LED lighting apparatus so as to perform the dimming control for the LED lighting apparatus.
Incidentally, when the TRIAC of the dimmer is turned on in a phase close to a peak of the AC voltage, the input current into the lighting device may rapidly increase. Thus, there is a possibility that an overcurrent may flow through the lighting device.